Geoffrey Rush reckons he only had to read up to page 15 of the Quills script before he decided to make the controversial new movie about the infamous Marquis de Sade. That's when he came across his first love scene with co-star Kate Winslet. And at a recent press conference with the two stars in Berlin, Winslet thanked her co-star by proceeding to wildly ravish the bemused but clearly impressed Australian Oscar nominee.

Of course the desired effect was to entertain the troops, to cause a stir and to keep up morale in promoting the film. And that is what the irrepressible Winslet is so good at. She doesn't flinch either. What about that pesky weight thing? The media's obsession with her size must be driving her mad . . . "Completely," she agreed, rolling her eyes indignantly in a later interview. The latest headline is that the 25-year-old is going skinny. "That's horses***!" She reached for a cigarette and announced: "I'm going to close this matter once and for all. I did an interview with a journalist in England who asked what I was doing right now and I said, 'Um, well, I'm just looking after [baby] Mia and attempting to get back into shape, because if I tried to go to work now I wouldn't get a job'. True, I gained 50-60 pounds [22-27kg] when I was pregnant, so of course I'm not going to get a job when I've just had a baby and I've got a stomach that hangs down to my knees. I wanted to get back to my pre-pregnancy weight, and that's what I've done. I'd hate myself skinny. I've been skinny. It's f***ing boring. And Jim [Threapleton, her husband] wouldn't fancy me anymore."

Other than being a little broader in the bow, Winslet, wearing little or no make-up and with her hair pulled back tight in a ponytail, was radiantly beautiful and obviously very, very happy. She seems to want to share her happiness with those around her, and this particularly happened on the set of Quills with Joaquin Phoenix.

Having just finished Gladiator, Phoenix came to Quills completely exhausted. Winslet, who plays the maid smuggling de Sade's text out of the asylum to which he's been banished, proved a big help. Phoenix takes the part of the asylum's pioneering abbe who advocates a libertine approach to mental illness. He recalled: "I'm standing there with the crew at 10 o'clock at night saying, 'I'm not coming back tomorrow, there's no way I can do this', and Kate's asking if she can bring me some tea. She's bringing tea and biscuits for everyone, throwing parties, she's just a really considerate woman. And you can see that in her acting. She's very giving. There's a great warmth about her." "It was my project to get Joaquin through the film," Winslet admitted, "because he was very tired and he was playing the hardest role of all of us."

You get the impression she is protecting the innocent 26-year-old who is bound for the big time. She has been through the grueling ordeal of fame herself. Winslet had not yet been nominated for an Oscar for Sense And Sensibility when she was cast in Titanic, alongside Leonardo DiCaprio. Nobody, not even the future "king of the world", James Cameron, had any inkling of Titanic's ultimate success. It certainly wasn't as if Winslet was looking for a blockbuster. "As an actress I'm slightly rebellious because I really like to go against the grain, to go against conformity. I don't really like to do things that people would expect me to do. Reading Titanic I loved the screenplay, I loved the role, and Jim Cameron's a genius director. It was just about the film and working with Leo. I mean how fantastic, and also I wanted to play an American. I love doing accents."

Titanic's success came as a shock to everyone and Winslet didn't know how to cope. "After Titanic everything turned upside down for a while and I didn't want that amount of pressure being put on me because I was not liking my job anymore. I was being turned into a commodity. I remember thinking how I've got to turn this around, because otherwise I'm going to suffer as a person and as an actor. So I made a very conscious decision to find something just tiny, tiny, tiny to do, hence Hideous Kinky, because I really needed to go and do a film that no-one approved of, that everyone thought was just a ridiculous idea, and just for myself. It was shooting in Morocco and it was in the sunshine and I could get a suntan, and if I hadn't have done that I wouldn't have met Jim [an assistant director on the film]. So it was good all round."

She has since come to appreciate the success of Titanic more. "I was researching for Holy Smoke and I was backpacking all over northern India and people knew who I was. They loved the film, it gave them so much, and I'm really grateful for that."

Yet as with Quills and Jude and Sense And Sensibility, in her upcoming films she plays a woman from the past - in Therese Raquin, based on a novel by Emile Zola; and in the romantic spy thriller, the code-cracking Enigma. "I'm getting there [more contemporary] though - Enigma's World War II," she protested. "The female roles are just stronger in period films. I read as many contemporary scripts as I do period ones, but the period ones just get me every time."

Quills opens on Thursday.